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UL rated 5 B:C Halocarbon extinguishers that will be used in transport category aircraft must pass 2 tests identified inDOT/FAA/AR-01/37 Development of a Minimum Performance Standard (MPS) for Hand-Held Fire Extinguishers as a Replacement for Halon 1211 on Civilian Transport Category Aircraft.

Hidden Fire Test

Seat Fire/Toxicity Test

The MPS guarantees extinguishers to replace halon 1211 will have equal fire performance and an acceptable level of toxicity (for decomposition products of the agent). Guidance for agent toxicity can be found in the advisory circular.

The MPS states that a permanent label be affixed to the extinguisher identifying FAA approval for use on board commercial aircraft.

Select a cargo extinguisher that meets the non-toxic use guidance for the aircraft cabin

If no cargo extinguisher meets the non-toxic use guidance for the aircraft cabin:

Consider installing a class C fire flooding suppression system in the cargo compartment or alternatives to handheld extinguishers that would provide effective fire protection.

Use the required UL Rating extinguisher.

Select the least toxic agent of the required UL rating. Place a Placard on or alongside the bottle stating: “Discharge of the entire contents of this size bottle into the occupied cabin area exceeds safe exposure limits. Use only the amount necessary to extinguish a fire”

A longer throw range of 10 feet or greater is needed to fight seat fires in large aircraft cabins and narrow body fuselages where the heat radiating from the ceiling may make it more difficult to get close to the fire.

A shorter throw range with a lower velocity discharge is less likely to cause splashing &/ or splattering of the burning material. Consider a shorter throw range for very small aircraft

Select a range that would allow the firefighter to effectively fight fires likely to occur.

The toxicity issues for extinguishing agents in portable fire extinguishers is the most important concern of the airline industry as indicated in over 111 responses to the User Preference Survey conducted by the FAA sponsored IASFPWG.

Total agent available from all required extinguishers should not be capable (assuming perfect mixing) of producing concentrations in the compartment by volume, at 70ºF (21.1ºC)when discharged at altitude (8,000 ft. P, pressurized Aircraft and 14,000 ft P, nonpressurized aircraft), that exceeds the agent’s safe exposure guidelines. (Note: Designing for altitude provides a large safety factor for ground use. No need for 120ºF correction)

Nonventilated passenger or crew compartments:

PBPK derived 5 minute safe human exposure concentration, if known.

If PBPK data is not available, the agent No Observable Adverse Effect Level (NOAEL) is to be used. (Note: UL 2129 allows use of a (sometimes higher) LOAEL Concentration)

Ventilated Compartments:

Use ventilation selector graphs to obtain the maximum agent weight per cubic foot allowed in the cabin. Tables are based on PBPK modeling of theoretical concentration decay curves & perfect mixing. If tables are not available, follow concentration guidelines for nonventilated compartments.

If Air change time is unknown or exceeds 6 minutes, use unventilated data (Prolonged exposure to these agents may be hazardous):

W/V = 0.0432 pounds/ft3 for pressurized cabins.

W/V = 0.0341 pounds/ft3 for Nonpressurized Cabins

Unpressurized Aircraft should descend at a minimum rate of 1,000 ft/minute if agent weights are greater than half the maximum safe weight for a given volume to avoid the life threatening hazards of hypoxia resulting from the agent displacing oxygen from the air in the compartment. This guidance should be followed regardless of ventilation rate.

Immediate descent to an altitude that is as low as practical is recommended for all aircraft to minimize the dangers of hypoxia and exposure to halogenated agents.

If Air change time is unknown or exceeds 6 minutes, use unventilated data (Prolonged exposure to these agents may be hazardous):

W/V = 0.0395 pounds/ft3 for Pressurized Cabins

W/V = 0.0312 pounds/ft3 for Nonpressurized Cabins

Unpressurized Aircraft should descend at a minimum rate of 1,000 ft/minute if agent weights are greater than half the maximum safe weight for a given volume to avoid the life threatening hazards of hypoxia resulting from the agent displacing oxygen from the air in the compartment. This guidance should be followed regardless of ventilation rate.

Immediate descent to an altitude that is as low as practical is recommended for all aircraft to minimize the dangers of hypoxia and exposure to halogenated agents.

Provides a simple mathematical solution to obtain data needed to develop perfect mixing ventilation tables which will provide maximum safe extinguishing agent weights for a range of compartment volumes and air change times.

Monte Carlo simulations of arterial blood concentration histories for 5 minute exposures to constant agent concentrations are used as input data for developing equations (95% confidence) for each extinguishing agent.

PBPK arterial blood data has been published for HFC 236fa and HFC 237fa which accounts for 95% (two standard deviations) of the simulated population having 5 minute arterial blood concentrations below the target concentration.

Equations can be developed for each agent, which transform agent concentration histories to arterial blood concentration histories in ventilated spaces.

Demonstrated to work for predicting blood concentration histories for exposures to a constant concentration of agent.

Has been validated for predicting blood concentration histories for exposures to changing concentrations of agent.